Heat 1 Tbs of the oil in a large skillet (or wok) on medium high heat. Add the onion and cook a minute or so, stirring frequently. You want it soft and just beginning to brown.
If the meat is raw, add it and cook a minute or so until done.
Add the vegetables and cook, stirring frequently, until crisp tender, a minute or two.
If the meat is cooked, add and heat through, another minute, stirring.
Add the garlic and stir a minute or less and then remove the meat and vegetables from the pan and put them in a bowl to keep while you cook the rice.
Heat the other 3 Tbs of oil in the pan until hot, then add the rice and stir 2-3 minutes. Add the beaten egg in and stir, cooking until done, another minute or so. Add the meat and vegetables and stir to heat through.